1. Field of the Invention
The present invention relates to a process for dissolution of calcium carbonate-containing solids (either in the form of a hard scale or a soft residue) in a treatment zone such as a swimming pool chlorinator using a lactic acid solution.
2. Brief Description of the Art
Chlorinated water is commonly used to sanitize swimming pools, spas, and hot tubs. Chlorinators such as the PULSAR.RTM. II chlorinator made by Olin Corporation provide a source of the chlorinated water for the pools and the like.
One of the most difficult problems in the use of chlorine solutions of hard water is the removal of calcium carbonate scale and residues from the operating surfaces of the chlorinator and the pool or the like. Removal of this scale and residue is difficult and time-consuming. In the past, the standard cleaning procedure was for the chlorinator to be emptied, rinsed, disassembled and its components cleaned with a mineral acid (preferably hydrochloric acid). This is time-consuming and costly. Moreover, when mineral acids such as hydrochloric acid are used, the potential of forming extremely irritating chlorine gas fumes, exist.
Accordingly, a better method of removing calcium carbonate solids from the chlorinator and the pool surface without having to disassemble the chlorinator and the risk of forming these chlorine gas fumes is needed. The present invention is a solution to that need.
Separately, lactic acid has been used as a calcium silicate scale remover for boilers. See Ecologically harmless technology for the chemical treatment of inside surfaces of boiler equipment with lactic acid, Zhuravleva, E. Yu., et al. Prom Energ., 7, 33-5; Method of removing calcium containing boiler scale and water circuit scale, Gruszkowski, H. et al. Polish Patent PL 145546 (30 Sept. 1988); and Cleaning and washing agent for boiler scale and deposits from heat exchange surfaces, Kwiatkowski, B. Polish Patent PL 140727 (30 May 1987).
Lactic acid also has been used in hard surface cleaners. See Cationic surfactants in organic acid-based hard surface cleaners, Roerig, H. and Stephan, R., Comun. Jorn. Com. Esp. Deterg. 21, 191-206.
Lactic acid has also been employed as a metal descaling agent. See Metal descaling agent, Negoro, E. et al., Japanese patent JP 54063107 (21 May 1979).
However, none of these references teach the use of lactic acid in the dissolving of calcium carbonate solids in the presence of aqueous chlorine solutions.